Ported Coyote Heads Dyno Test - Killer Coyote Cardio

Adding CNC-ported heads to a Coyote powerplant

Richard Holdener

August 3, 2012

If there’s one downside to the new lineup of Mustang engines, it’s the small bore spacing and the attending limit it imposes on available displacement. But rest assured, even at just 5.0 liters, the 5.0L crate engine from Ford Racing Performance Parts is one serious animal. Thanks to the FRPP Controls Pack, the crate engine was a plug-and-play operation, including control over the drive-by-wire throttle and variable cam timing. Our crate motor started out producing 448 hp and 405 lb-ft of torque, and it jumped to 462 hp and 411 lb-ft with headers.

When we first started this Killer Coyote series, we wanted to illustrate as many of the performance components available, so we followed up with a bonanza of bolt-ons, including Zex nitrous, a Kenne Bell supercharger, and we even swapped the stock cams for a set of Stage 2 NSR grinds from Comp Cams (PN 191100). The nitrous upped output to 554 hp, while the Kenne Bell Twin Screw pushed this the Coyote to 704 hp and 549 lb-ft of torque at less than 10 psi.

Given the impressive output, we were thankful for the Aeromotive A1000 fuel system employed on the engine dyno. The cams increased horsepower substantially, especially when combined with a new air intake from JLT. Equipped with cams and JLT air intake, the little 5.0L produced 515 hp and 450 lb-ft of torque.

It is understandable to expect big horsepower numbers from a four-valve motor, but what really impressed us was the torque production. Exceeding 100 hp per liter (1.705 hp per cubic inch) is impressive, but this street motor offered BMEP numbers (effectively torque output relative to displacement) of 212, and on pump gas no less!

Put into perspective, most street motors have BMEP numbers in the low-to-mid 170s with very powerful (high-compression) combinations touching 200. Exceeding 200 often takes a dedicated race motor with 13.0:1-plus compression, a solid-roller cam, and dry-sump oiling system. This Coyote offered the best BMEP number we’ve ever tested on a street motor on pump gas.

Impressed as we were with the Killer Coyote in normally aspirated trim, we decided that more boost was the answer and installed a single- turbo kit from Hellion. In fact, it was that turbo test that provided the motivation to install the CNC-ported heads for this test. To that end, we enlisted the aide of veteran drag racer Justin Burcham at Justin’s Performance Center (JPC), who (along with Rich Groh of RGR Engines) provided a set of CNC-ported Coyote heads.

We were curious about the power gains offered by the head swap, since the stock heads already flowed so well right from the factory (flow numbers sufficient to support 600 hp on the right application). Since our mild Coyote was making nowhere near that much power, we couldn’t help but question the logic of extra cardio for our Coyote. Our concerns were quickly put to rest.

The Stage 1 heads supplied by JPC and RGR featured full CNC porting. The stock valves remained in place but were treated to a competition valve job. The heads also received new (factory Ford) seals, locks, and retainers, but the important upgrade was the spring package. Given our past experience with the valve float issue, we were excited about the increase in valvespring pressure.

Using the stock retainers and keepers, the new springs offered 80 pounds of seat pressure and 200 pounds of open pressure. These spring rates may not seem like much compared to race hardware for a traditional small-block, but remember, the Coyote sported four small valves compared to a pair of larger (and heavier) valves in the conventional small block. It’s the small, lightweight valves that allowed the engine to utilize such (relatively) light spring pressure. Though we did not flowbench test the heads, JPC claims that the porting improved the flow rate of the Coyote heads from just under 300 cfm to over 330 cfm (roughly 10 percent).